UrlShortcut

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Description

Summary

UrlShortcut is a simple PHP script that let's you maintain a database of "shortcut" URLs.

This allows you to publish URLs to friends that are not extra long, with the purpose of either having easier to type URLs or simply to place URLs in email and avoid the URL being split on several lines. You can also use it as a repository of URLs to consult later or as a reminder of URLs to add to your favorite blog.

What is it?

UrlShortcut is a simple PHP script that let's you maintain a database of "shortcut" urls.
When a browser visits one of these short URLs, the PHP script will redirect the browser to the original URL immediately.

URL redirections can generally be setup directly in your web server's configuration (IIS, Apache, etc.). Unfortunately, this is generally a manual process that is hard to automatize and also requires administrator access to the web server computer and/or the web server account. On the other hand, UrlShortcut can be installed easily on any web server that has PHP support, such as home page typically provided by ISPs.

Requirements

To use UrlShortcut, you need:

• A web server with PHP support.
• PHP must have been compiled with DBA support, the dbm-style database abstract layer.

By default, the script uses the "db4" handler. This can be changed as described later.

Installation

Notes: this manual described steps for installation on a typical Linux box. Configuration on other systems should be similar. Please refer to your system maintainer or your operating system vendor for details.

To install, simply untar the archive under your public_html and rename the directory to what you want to see in the final URL. For example:

cd ~/public_html
tar xvzf UrlShortcut-1.0.tgz
mv UrlShortcut-1.0 url

This will make UrlShortcut available as the following URL:

http://www.example.org/url?1

The archive is composed of the following files:

Configuration is achieved by editing common.php and modifying the following defines at the top of the file:

DB_HANDLER preference:

• This string represents the name of the DBA handler to use.
• Consult the PHP Manual for DBA to get a list of possible handlers: http://www.php.net/manual/en/ref.dba.php.
• Not all handlers are available on a given system. This depends on how PHP was configured and what libraries are available on your system.
• On most recent Linux boxes, the "db4" handler should be the default with PHP 4.3.2; for older version of PHP, the "db2" handler can be used. Otherwise the "flatfile" format should be your last chance.

DB_FILE preference:

• This string contains the relative path of the database file.
• By default the file will be located in the "data" directory located at the same place than the script. You can change this here.
• DB_FILE is relative path, that is the absolute directory where the script *executes* will be prefixed to the DB_FILE path.
• You must ensure that your web server has write access to the directory and can create a file there.

Usage

The following discussion assumes UrlShortcut has been installed as described above and the service is available at the following URL:

http://www.example.org/url/

1- Creating Shortcuts

To use UrlShortcut, you must first create a shortcut. You can do this by accessing the create.php script and providing the target URL directly on the query string, like this:

http://www.example.org/url/create.php?http://www.alfray.com/projects/UrlShortcut/

The URL must begin with "http://" to be accepted.

Since typing such an URL is annoying, the best way to create a shortcut is to place a bookmark in the toolbar of your JavaScript-enabled browser:

• Drag this link "Create Shortcut" to your browser's toolbar (Internet Explorer, Mozilla, FireFox, etc.).
• Edit the bookmark and replace "www.example.org/url" by the real location of your page.
• Now simply navigate to any page and press the bookmark "Create Shortcut" to create a new shortcut to the current page.

You will really enjoy and take full advantage of the simplicity of creating shortcuts once you take the necessary step to configure your web browser.

Once a shortcut has been created, a page will display the result shortcut, as this:

The following shortcut: http://www.example.org/url?1 has been created and registered for the following URL: http://www.alfray.com/projects/UrlShortcut/ List all existing keys Alfray's UrlShortcut v1.0

The first link is what you want to use, copy/paste in emails, etc.

Note that UrlShortcut does not duplicate keys. If you try to create a new shortcut later with the same target URL, you will receive the previous shortcut URL. That means it is safe to call the creation script as many times as you want with the same target URL.

In the shortcut URL generated above, "1" is what makes the shortcut URL unique. This identifier is created by incrementally increasing a counter. The first value is 1 (the value 0 is never used). The counter value is encoded in base 34 using digits and lower-cap letters except letters "o" and "l" (L) which can be easily confused with 0 (zero) and 1 (one). If you need to memorize or write down the shortcut URL, the identifier is all you need.

2- Listing Shortcuts

Once you have created several shortcut URLs, you may not remember where each shortcut points to. The list page will show you that. It is available via a link at the bottom of the create page. To view the list, you simply need to browse this URL:

http://www.example.org/url/list.php

The result will look like that:

[1] => http://www.alfray.com/projects/UrlShortcut/ [2] => http://www.alfray.com/ [3] => http://www.alfray.com/projects/nerdkill/index.html [4] => http://ralf.alfray.com/.izumi/ Alfray's UrlShortcut v1.0

3- Using Shortcuts

To use a shortcut, simply enter the shortcut URL in any browser. The script will order the browser to redirect to the target URL, if such a shortcut exists in its database. If not, the user will be presented with an informative message.

If the target URL is no longer valid, UrlShortcut still tries to redirect the browser to the specified URL. Depending on its configuration, the browser will display an error message indicating the page cannot be found.

Limitations

UrlShortcut has the following limitations:

• It has only been tested with Apache 1.3.29 and PHP 4.3.3.
  • The script is simple enough to work with earlier versions of PHP, probably up to PHP 4.1.x, provided that some minimal DBA support is compiled in PHP.
  • The script should also work with any other web server that has PHP support, such as IIS although this has not been tested and cannot be guaranteed.

• As explained earlier, PHP must have DBA compiled in.

• Anonymous issue & URL discovery hacking:
  • Unless you configure your web server otherwise, anybody can access the URL redirector.
  • It is strongly suggest that you protect the list.php and create.php script, unless you are providing a public service. The accompanying template.htaccess shows how to limit access to these files by IP address.
  • Since shortcut URLs are created in a linear way, it is trivial to "discover" any other URL by simply injecting a random number on the URL query line of the redirector. Unless you protect access to the index.php script, anybody can use the service with either a legitimate shortcut URL or a crafted one. Since the redirector has no previous knowledge of who is allowed to use it, by default it allows anybody to do so and cannot, by design, distinguish between valid uses and abuses.

• There is currently no mechanism to remove a shortcut URL nor to update its value in case the target page has moved:
  • Manually updating an URL or delete it is a feature that may be provided in a future release.
  • By design, it is not possible to automatically discover if a page has moved and update its URL in the shortcut database.
  • You can remove all shortcuts at once by simply deleting the database file on the server.

License

UrlShortcut is distributed under the terms of the General Public License (a.k.a. GPL).

I am not a lawyer and I find licenses generally obscure to read, so what it all means is:

• UrlShortcut is free software, it can be used for either personal, academic or commercial purposes at absolutely no cost.
• It comes "as-is". No guarantee, support, maintenance or installation help is implied.
• You are free to add any feature that you think is missing, or change the source code or the look to match your own needs. I'm interested in learning about any feature you add, yet I make no promise I'll actually reuse your code. If you redistribute your own version, please use the same license and make it easy to differentiate your sources from mine.
• I love positive feedback and positive criticism. An extended to-do list of things I'd like to see in the software at some point is included in the source archive. Of course there is no written schedule for this, it all depends on my free time and my creativity. If you need something that is not on this list, please ask gently.
• Your respect will earn you mine.

News

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Contact

UrlShortcut is developed and maintained by